The X-ray fluorescence analysis method is used to identify the kinds of minor components (e.g. metallic elements) contained in a resin product or foodstuff and determine their quantities. The kinds of minor components are identified from the energy of the detected fluorescent X-rays, while their quantities are determined from the intensity of the fluorescent X-rays.
The FP method is one of the methods for the quantitative determination of sample components (for example, see Patent Literatures 1 and 2). Unlike the calibration curve method which requires the task of previously creating a calibration curve by performing measurements on a large number of standard samples composed of similar substances to the measurement target sample at different concentrations, the FP method does not require such a task and therefore is suitable for an analysis of a sample containing unknown kinds of components.
In the FP method, the content of each component is determined from a measured value of the intensity of the fluorescent X-rays by means of a theoretical formula for calculating the intensity of the fluorescent X-rays. However, no fluorescent X-rays can be detected from organic substances. Therefore, as in the case of resin products, when the principal component is an organic substance, the quantitative value of the principal component is determined by subtracting, from the entire quantity, the previously determined quantitative values of the components other than the principal component.